Abstract: An electret condenser includes a fixed film 110 including a conductive film 118 to be an upper electrode, a vibrating film 112 including a lower electrode 104 and a silicon oxide film 105 to be an electret film, and a silicon oxide film 108 provided between the fixed film 110 and the vibrating film 112 and including an air gap 109. Respective parts of the fixed film 110 and the vibrating film 112 exposed in the air gap 109 are formed of silicon nitride films 106 and 114.

Abstract: A speaker includes a thermoacoustic module, an amplifier circuit board, and a frame. The thermoacoustic module includes a sound wave generator, at least one first electrode and at least one second electrode. The at least one first electrode and the at least one second electrode are electrically connected to the sound wave generator. The sound wave generator includes a carbon nanotube structure. The amplifier circuit board is electrically connected to the carbon nanotube structure by the at least one first electrode and at least one second electrode. The frame secures the thermoacoustic module and the amplifier circuit board.

Abstract: The present invention provides an electret transducer with solar power. The provided electrets transducer includes a solar power supply device, an amplifier circuit having a first input terminal coupled to the solar power supply device and a second input terminal coupled to an audio signal input terminal, and an electret loudspeaker coupled to an output terminal of the amplifier circuit. The amplifier circuit receives a first voltage level via the first input terminal and boosts the first voltage level to a second voltage level, and receives a first audio signal via the second input terminal and amplifies the first audio signal to a second audio signal. The electret loudspeaker coupled to the output terminal of the amplifier circuit receives the second audio signal and outputs a sound corresponding to the second audio signal.

Abstract: A digital sound system suitable for a digital speaker device for directly converting analog sound by a circuit using a ?? modulator and a mismatch shaping filter circuit to output a plurality of digital signals and a plurality of speakers driven by the plurality of digital signals. A digital speaker driving device includes a ?? modulator, a post filter, s driving circuits, and a power supply circuit to supply power to the ?? modulator, the post filter and the s driving elements and the s driving circuits are adapted to s digital signal terminals.

Abstract: A thermoacoustic device includes first electrodes, a first conductive element, second electrodes, a second conductive element, first insulators, second insulators and a thermoacoustic film. The first conductive element is electrically connected with the first electrodes. The second conductive element is electrically connected with the second electrodes. The first insulators connect the first electrodes to the second conductive element while insulating them from each other, and the second insulators connect the second electrodes with the first conductive element while insulating them from each other. The thermoacoustic film is electrically connected with the first electrodes and the second electrodes.

Abstract: The invention provides an electronic device and an electro-acoustic transducer thereof. The electronic device includes a main body and an electro-acoustic transducer carried by the main body. The electro-acoustic transducer includes a first electret diaphragm, a second electret diaphragm and a plate. The first electret diaphragm generates vibrations according to a first electrical signal and the second electret diaphragm generates vibrations according to a second electrical signal. The plate includes a plurality of holes formed thereon and is disposed between the first electret diaphragm and the second electret diaphragm. Additionally, the electronic device further includes a decorative layer formed on the first or the second electret diaphragm.

Abstract: An acoustic sensing element has a substrate that includes a back chamber, a vibration electrode plate that is provided in a surface of the substrate while being opposite an upper surface opening of the back chamber, and a fixed electrode plate that is provided opposite the vibration electrode plate, an acoustic hole being made in the fixed electrode plate. The acoustic sensing element outputs an electric signal based on an electrostatic capacitance change generated between the vibration electrode plate and the fixed electrode plate by a displacement of the vibration electrode plate. A lower surface of the back chamber is closed into a pouched shape by the substrate.

Abstract: The present invention provides an electret transducer with solar power. The provided electrets transducer includes a solar power supply device, an amplifier circuit having a first input terminal coupled to the solar power supply device and a second input terminal coupled to an audio signal input terminal, and an electret loudspeaker coupled to an output terminal of the amplifier circuit. The amplifier circuit receives a first voltage level via the first input terminal and boosts the first voltage level to a second voltage level, and receives a first audio signal via the second input terminal and amplifies the first audio signal to a second audio signal. The electret loudspeaker coupled to the output terminal of the amplifier circuit receives the second audio signal and outputs a sound corresponding to the second audio signal.

Abstract: A speaker device including a transparent speaker and a light source module is provided. The transparent speaker is thin, soft, and has a low driving voltage. Light is emitted from a front side of the speaker panel, and transmitted in the same direction as the sound. Thus, the light is emitted along with the sound. The speaker device can be used as an indoor wall-painting or as a large advertisement poster for more visual effects to the viewer.

Abstract: A thermoacoustic device includes a first electrode, a second electrode and a sound wave generator. The first electrode includes a first electrical conductor and a first conductive adhesive layer located on the first electrical conductor. The second electrode includes a second electrical conductor and a second conductive adhesive layer located on the second electrical conductor. The sound wave generator includes a carbon nanotube structure, and the sound wave generator is electrically connected to the first electrical conductor and the second electrical conductor via the first and second conductive adhesive layers. The adhesive layers permeate into the carbon nanotube structure.

Abstract: An electrostatic speaker system including at least one electrostatic speaker element having a pair of stators and a diaphragm therebetween, each of the stators and the diaphragm having an least one electrically conductive portion. The conductive portion of the diaphragm is patterned as a mesh, which may include gaps, and a conforming layer overlying the conducting portion of the diaphragm and disposed so as to cover gaps in the mesh. A speaker drive circuit provides soft clipping of the audio input signal so that the audio signal applied between the diaphragm and the stators does not exceed the maximum acceptable level that can be applied between the diaphragm and the stators of at least one speaker element.

Abstract: An electret electrode is constituted by forming a conductive film on a substrate, laminating a first insulating film and a second insulating film alternatively on the conductive film, and then disposing electret films in which a lower surface, an upper surface and a side surface are covered with a third insulating film and a fourth insulating film. Existing of the first insulating film and the second insulating film between the electret films and the conductive film enables an increase in electric field intensity in the film when the same electric charge is retained, while enables an increase in surface charge density (surface potential) when the electric field intensity is the same.

Abstract: A compound membrane (100) for an acoustic device (200), the compound membrane (100) comprising a first layer (101) and a second layer (102), wherein a value of Young's modulus of the second layer (102) does not vary more than essentially 30% in a temperature range between essentially ?20° C. and essentially +85° C.

Abstract: The present invention relates to an electrostatic speaker including a fixed electrode and a diaphragm that is arranged with a predetermined gap from the fixed electrode and has a plurality of ventilation holes. The ventilative diaphragm reduces air resistance caused by the ground effect between the fixed electrode and the diaphragm, and increases the sound pressure output from the speaker. As a result, the ventilative diaphragm makes it possible to obtain a uniform frequency reproduction characteristic over the entire frequency range. In particular, when the diaphragm is made from Korean paper, it is possible to effectively reduce the ground effect occurring between the fixed electrode and the diaphragm due to the air permeable characteristic of the Korean paper and the air resistance due to a surge input signal, while satisfying physical characteristics of the existing diaphragm. In addition, since the Korean paper has high formability, it is possible to easily form the diaphragm in a hemispherical shape.

Abstract: A device includes a first wafer, a second wafer, a gasket bonding the first wafer to the second wafer to define a cavity between the first wafer and the second wafer, and an acoustic transducer disposed on the first wafer and disposed within the cavity between the first wafer and the second wafer. One or more apertures are provided for communicating an acoustic signal between the acoustic transducer and an exterior of the device. An aperture may be formed in the cavity itself, or the cavity may be hermetically sealed. An aperture may be formed completely through the first wafer and located directly beneath at least a portion of the acoustic transducer.

Abstract: An electrode connection structure of a speaker unit is provided. The speaker unit includes at least one electrode layer, which is made of a conductive material, or made of a non-conductive material with a conductive layer formed on a surface thereof. The electrode connection structure includes a conductive electrode and an adhesive material. The conductive electrode is used for providing power supply signals for the speaker unit to generate sounds. The adhesive material adheres the conductive electrode in parallel with a surface of the electrode layer. The adhesive material has adhesive characteristics, so as to electrically connect the conductive electrode and the electrode layer, in which the adhesive material is adhered to a side of the surface of the electrode layer closely adjacent to the conductive electrode with a certain area.

Abstract: The present invention relates to a microphone that includes a housing and a diaphragm and backplate located with the housing. The housing has a sound port for receiving the sound. The diaphragm undergoes movement relative to the backplate, which it opposes, in response to the incoming sound. The backplate has a charged layer with a first surface that is exposed to the diaphragm and a second surface opposite the first surface. The backplate further includes a conductor for transmitting a signal from the backplate to electronics in the housing. The conductor faces the second surface of the charged layer. To minimize the charge degradation created by contact with or infiltration of foreign materials, the first surface, the second surface, or both surfaces of the charged layer includes a protective layer thereon.

Abstract: An electronic device is provided, including a conductive substrate, an electret diaphragm, a plurality of spacers, a first electrode, and two second electrodes. The conductive substrate has a plurality of openings. The spacers are disposed between the conductive substrate and the electret diaphragm to define an acoustic projecting portion and two acoustic receiving portions on the electret diaphragm. The first electrode is disposed on the acoustic projecting portion and coupled with the conductive substrate for generating an acoustic signal. The second electrodes are disposed on the acoustic receiving portions and coupled with the conductive substrate, wherein the acoustic receiving portions receive the acoustic signal and vibrate to vary an electrical field between the second electrodes and the conductive substrate.

Abstract: A method for manufacturing electret diaphragms is provided. First, a dielectric film is attached to a frame by an adhesive material and a fastening element grips the peripheral area of the dielectric film on the frame. Afterward, the dielectric film is subjected to a metal sputtering process to form a conductive material layer thereon. Finally, the dielectric film is subjected to a polarizing process thereby forming an electret diaphragm.

Abstract: A microphone-capsule includes a vibrator implemented by a conductor having a flat vibration surface, a dielectric-polarization plate that is defined by a flat first principal surface facing the vibration surface of the vibrating plate and a second principal surface facing parallel to the first principal surface and in which polarization directions are aligned, a back electrode joined to the second principal surface of the dielectric-polarization plate, and an induced-charge measuring unit configured to measure the charges induced between the vibrating plate and the back electrode, in association with the displacement of the vibration surface. The induced-charge measuring unit includes an amplifier connected to the back electrode and an output circuit connected to the amplifier.

Abstract: A slender-type diaphragm longer in a longitudinal direction and shorter in a transversal direction in relation to the longitudinal direction, has a base member and a slant member. The base member has a pair of extending members provided in parallel in the longitudinal direction as facing each other, and a curved section that protrudes toward a first side of the diaphragm in a vibration direction of the diaphragm from a first plane that includes the extending members, the vibration direction being perpendicular to the longitudinal and transversal directions. The slant member has a slant surface in relation to the first plane and connected to the base member in a manner that the slant member surrounds the base member in a second plane parallel to the first plane, the slant member having a curved surface in a cross section thereof in relation to a cross section of the base member in the transversal direction.

Abstract: A speaker apparatus includes an acoustic vibration plate, and an actuator mounted to the acoustic vibration plate such that one end and the other end thereof, in a driving axis direction, exist in a plate surface of the acoustic vibration plate. The actuator applies vibration to the acoustic vibration plate to play back sound. The speaker apparatus enables a sound image to uniformly spread over the entire plate surface of the acoustic vibration plate. In addition, the entire speaker apparatus can be made compact.

Abstract: A micro-electro-mechanical transducer (such as a cMUT) is disclosed. The transducer has a substrate, a top plate, and a resilient structure therebetween. The resilient structure has multiple connectors distributed over the device element area to vertically transport the top player with distributed support. The resilient structure may be cantilevers formed using a middle spring layer covering cavities on the substrate. Connectors define a transducing space below the top plate. The resilient structure enables a vertical displacement of the connectors, which transports the top plate in a piston-like motion to change the transducing space and to effectuate energy transformation. No separate cells are necessary for each addressable transducer element. Multiple device elements can be made on the same substrate.

Abstract: A condenser microphone is disclosed. The condenser microphone includes a substrate having a cavity, a backplate connected to the substrate, a diaphragm facing to the backplate, and an anchor supporting the diaphragm. A first gap is formed between the diaphragm and the backplate. A groove is arranged on the anchor and the diaphragm partially covers the groove. The diaphragm and the groove forms a second gap communicating with the first gap.

Abstract: An electro-acoustic transducer is disclosed. The electro-acoustic transducer includes an electret diaphragm, an orifice plate and a plurality of dividing structures. The dividing structures, disposed between the electret diaphragm and the orifice plate, are cross-shaped. Each of the dividing structures includes two extending portions intersecting with each other.

Abstract: An assembly structure of flat speaker including at least two speaker units and one connecting structure is provided. Each speaker unit includes a first electrode, a vibrating film, and a second electrode. The connecting structure includes two conductive layers, and a first insulating layer. A first conductive layer is connected the first electrode through a contact area, and each has a first length and a third length parallel to the contact area. A second conductive layer is connected the second electrode through a contact area, and each has a second length and a fourth, a fifth length parallel to the contact area. The third length is less than or equal to a sum of the first lengths of the speaker units. A sum of the third, the fourth, and the fifth length is less than or equal to a sum of the first and second lengths.

Abstract: A sound wave generator includes a speaker control circuit and a speaker. The speaker control circuit includes a signal generating unit that is configured to generate an electric signal having a humming frequency property. The humming frequency property includes a plurality of frequencies that have an overtone relationship with respect to A Hz and are pitched at the A Hz, the A Hz being a target generation frequency and corresponding to a low pitch frequency in an audible range. The speaker generates a sound wave from the electric signal by applying the electric signal to a vibration plate that produces the sound wave.

Abstract: Provided is a method of manufacturing a capacitive electromechanical transducer, including: forming a lower electrode layer on a substrate; forming a sacrificial layer on the lower electrode layer; forming by application a resist layer on the sacrificial layer to form a cavity pattern; forming an insulating layer above regions including a region that contains the resist layer used to form the cavity pattern, and then removing a part of the insulating layer that is formed above the resist layer along with the resist layer, thereby leaving the insulating layer in the other regions than the region where the cavity pattern has been formed; forming a vibrating film above the region where the cavity pattern has been formed and the regions where the insulating layer remains; and removing the sacrificial layer to form a cavity.

Abstract: In one aspect, a boot located inside a mobile device holds a microphone. The boot has a straight, front chamber section whose mouth is aligned (vertically and horizontally) with a microphone-associated, acoustic case opening in a sidewall of the outer housing of the device. In another aspect, the front chamber section is defined by a front sidewall on whose outer surface a circumferential rib is formed. This portion of the boot sidewall is disposed within a tube section (which may be formed in the sidewall of the device's outer case), to form an acoustic seal around the mouth of the boot. Other embodiments are also described.

Abstract: A device includes a substrate and a transducer attached to the substrate, wherein the substrate includes a surface to which the transducer is attached and at least one edge member extending along at least a portion of the outside edge of the surface. The surface can be a generally planar surface. The edge member is stiffer than the surface. In several embodiments, the transducer is adapted to vibrate. The transducer can, for example, be selected from the group consisting of a piezoelectric transducer, an electrostrictive transducer and a magnetostrictive transducer. Preferably, the transducer is attached to the surface of the substrate by a metallic bonding agent and, more particularly, by welding.

Abstract: An integrated circuit structure includes a capacitor, which further includes a first capacitor plate formed of polysilicon, and a second capacitor plate substantially encircling the first capacitor plate. The first capacitor plate has a portion configured to vibrate in response to an acoustic wave. The second capacitor plate is fixed and has slanted edges facing the first capacitor plate.

Abstract: A microphone unit includes a substrate. The substrate includes a first face formed with a first recess, a second face opposite to the first face, and a through hole communicating the second face to a bottom part of the first recess. A diaphragm unit includes a diaphragm, and at least a part of which is disposed in the first recess so that the diaphragm opposes the through hole.

Abstract: An acoustic transducer includes a diaphragm defining a center portion and a supporting portion surrounding the center portion and a coil attached to the diaphragm and defining a pair of leading wires. The center portion defines a lower surface connected to the coil, an upper surface opposite to the lower surface, and at least a pair of protrusion portions extending from the lower surface toward the upper surface for receiving the leading wires of the coil.

Abstract: A microelectromechanical system microphone structure including a substrate, a first device and at least one second device is provided. The first device is disposed on the substrate and including a first upper electrode and a first lower electrode disposed between the first upper electrode and the substrate. The second device is disposed on the substrate, surrounding the first device and including a second upper electrode and a second lower electrode disposed between the second upper electrode and the substrate. The second upper electrode includes a plurality of first conductive layers and first plugs. The first conductive layers are arranged in steps, and the first plug is disposed between the adjacent first conductive layers. The second lower electrode includes a plurality of second conductive layers and a plurality of second plugs. The second conductive layers are arranged in steps, and the second plug is disposed between the adjacent second conductive layers.

Abstract: A wireless communication system based on a directional speaker is disclosed. The system can include an interface unit and a base unit. The audio signals from the speaker can be generated by transforming ultrasonic signals in air. This allows the production of directional audio signals even when the aperture of the speaker has dimensions in the order of a few centimeters. The audio signals from the speaker can be heard hands-free. Further, privacy protection is enhanced. In one embodiment, the interface unit can be attached or integrated to a piece of clothing at the shoulder of the user, with the audio signals from the speaker directed towards one of the user's ears. The wireless communication system can be applied to a number of different areas, including a communication device, such as a cell phone; a hearing aid; an entertainment system; and a computation system, such as a personal digital assistant or a computer.

Abstract: An electrostatic loudspeaker (ESL) system includes a damping screen adjacent an outside surface of at least one of its stators to reduce distortion of acoustic output rendered by the loudspeaker's diaphragm, including effects of resonance of the diaphragm. A resilient excursion limiter placed adjacent an inside surface of at least one of the stators prevents contact of the diaphragm with the stator. A conductive portion of the diaphragm is printed with a conductive ink layer that includes conductive nanofibers. The loudspeaker system includes a dipole-radiating ESL element, an unbaffled or partially baffled dynamic loudspeaker and a baffled monopole-radiating dynamic loudspeaker (subwoofer), all essentially co-planar. The unbaffled or partially baffled dynamic loudspeaker provides a smooth transition in sound between the dipole-radiating ESL element and the monopole-radiating subwoofer.

Abstract: A speaker module for a portable terminal is provided. The speaker module includes an upper case constituting a part of a module housing, a speaker unit, including a magnetic body, a voice coil and a vibration plate, formed in the upper case and a vibration motor, which is installed in the upper case and on one side of the speaker unit. The speaker module as structured above can secure a sufficient sound pressure and a sound volume in a portable terminal having a slim construction, makes it easier to secure space for installation within a portable terminal having a small size and slim construction in such a manner that a vibration motor, etc. are received and integrated in a module housing, and can improve the quality of sound in a portable terminal by achieving improved smoothness of output sound pressure in an audio frequency range.

Abstract: A speaker is integrally formed with a multi-layered printed circuit board. The printed circuit board includes a flexible membrane layer with a conductive pattern thereon. Positive and negative elements are disposed on opposing sides of the flexible membrane. A drive circuit connects to the flexible membrane layer and applies current to the flexible membrane layer responsive to an audio signal to generate audible sounds.

Abstract: An acoustic transducer, specifically an electrostatic loudspeaker (ESL) providing curvature in two directions for improved dispersion of sound waves. The compound curvature also provides a virtual focus of the propagated sound waves for accurate reproduction of musical program material recorded with standard single-point microphones. The highly directional nature of high frequency sound waves requires that a flat or cylindrical electrostatic transducer must be physically tall to allow a listener to either recline or stand. The two-axis curved structure enables a compact form of ESL to be realized, including bookshelf type loudspeakers whereas all known commercial units are comparable in height to that of a human listener. The individual curved ESL panels can also be readily combined to create larger transducer assemblies including omni-directional units.

Abstract: A speaker includes a base, a diaphragm, a separating module, a first electrode set and a second electrode set. The base and a porous structure are formed a cavity. The diaphragm is disposed in the cavity and includes a first part and a second part. The separating module is located in the cavity and contacts the diaphragm to separate the cavity into the first and the second chambers. The first electrode set disposed in the first chamber is connected to a first sound source signal, such that the first part of the diaphragm is vibrated and the first sound source signal is exported from the first chamber. The second electrode set disposed in the second chamber is connected to a second sound source signal, such that the second part of the diaphragm is vibrated and the second sound source signal is exported from the second chamber.

Abstract: Provided are a micro-electromechanical systems (MEMS) microphone and a method of manufacturing the same. A manufacturing process is simplified compared to a conventional art using both upper and lower substrate processes. Since defects which may occur during manufacturing are reduced due to the simplified manufacturing process, the manufacturing throughput is improved, and since durability of the MEMS microphone is improved, system stability against the external environment is improved.

Abstract: A device (100) for generating a vibration source driving signal (DS) is described, which device (100) comprises an input (101) for receiving an input signal (IS) and an output (102) for providing said driving signal (DS), generating means (103; 803) for generating a control signal (CS) which is representative of dynamic signal changes of the input signal (IS), and a processing unit (105; 201; 301; 401; 804) adapted to process a source signal (SRS; IAS) based on the control signal (CS) yielding said driving signal (DS).

Abstract: An electrostatic loudspeaker includes a front stator, first and second substantially conductive diaphragms, a center stator and a back stator. The front stator is connected to a safe reference potential such as earth ground. The first diaphragm, the center stator and the back stator are connected to individual positive, non equal DC bias voltages, referenced to the front stator. The second diaphragm is connected to a negative DC bias voltage. A high voltage audio signal, which is referenced to the front stator, is superimposed to the bias voltage of the center stator. The electrostatic loudspeaker can be driven by a single ended audio source. The electrostatic loudspeaker further features an improved electrical safety level.

Abstract: A driving interface device adaptive to a flat speaker is introduced herein. The driving interface device is coupled with an external sound source for receiving sound signals, and boosts voltage levels of the sound signals to drive the thin flat speaker without using an external power source. In one embodiment, an impedance component is provided in the driving interface device for coupling to the external sound source, so as to drive the flat speaker.

Abstract: The invention provides an integrated circuit attached to a microphone. In one embodiment, the integrated circuit comprises a buffer, a gain stage, an analog-to-digital converter (ADC), and a memory module. The buffer buffers a first signal generated by the microphone, and outputs the first signal as a second signal. The gain stage amplifies the second signal according to an adjustable gain to obtain a third signal. The analog-to-digital converter converts the third signal from analog to digital to obtain a fourth signal as an output of the integrated circuit. The memory module stores the adjustable gain and outputs the adjustable gain to the gain stage for controlling amplification of the gain stage.

Abstract: A cost-effective technology for implementing a micromechanical component is provided, whose layer construction includes at least one diaphragm on the upper side and at least one counter-element, a hollow space being formed between the diaphragm and the counter-element, and the counter-element having at least one through hole to a back volume. This back volume is formed by a sealed additional hollow space underneath the counter-element and is connected to the upper-side of the layer construction by at least one pressure equalization opening. This component structure permits the integration of the micromechanical sensor functions and evaluation electronics on one chip and is additionally suitable for mass production.

Abstract: An electret condenser microphone includes: a substrate 13 in which an opening 25 is formed; an electret condenser 50 connected to one face of the substrate 13 so as to close the opening 25 and having an acoustic hole 12 and a cavity 2; a drive circuit element 15 connected to the one face of the substrate 13; and a case 17 mounted over the substrate 13 so as to cover the electret condenser 50 and the drive circuit element 15. Electric contact is established at a joint part between the electret condenser 50 and the substrate 13. The acoustic hole 12 communicates with an external space through the opening 25. The cavity 2 and an internal region of the case 17 serve as a back air chamber for the electret condenser 50.

Abstract: A structure of an electrostatic speaker and a manufacturing method thereof are provided. In the electrostatic speaker, an electrode and a vibrating film are disposed closely, and electrostatic force of the vibrating film may make the vibrating film contacting with the electrode such that the speaker would fail to generate the sound. Thus, the invention provides a spacer structure and a manufacturing method thereof. Various patterning or height changes and other designed are performed to place the spacer between the electrode and the vibrating film, so as to prevent the electrode from contacting with the vibrating film. The disposition of the spacer is expected to enhance frequency response or sound volume of the speaker.

Abstract: An edge portion includes a center portion, one end and an other end. As seen in a cross section of a vibration plate in the radial direction, the center portion, the one end and the other end each are formed in a circular arc such that the edge portion forms a convex so as to protrude in a direction in which the protruding shape protrudes. The radius of curvature of the circular arc of the center portion is not less than the radius of curvature of the circular arc of each of the one end and the other end. Accordingly, a vibration plate allowing a decrease in the lowest resonance frequency while suppressing the edge portion from being brought into a tensioned state, a speaker unit provided with the vibration plate and a portable information terminal can be provided.

Abstract: Actuator apparatus for generating a physical effect, at least one attribute of which corresponds to at least one characteristic of a digital input signal sampled periodically in accordance with a clock, the apparatus comprising at least one array of moving elements each constrained to travel alternately back and forth along a respective axis in response to an alternating electromagnetic force applied to the array of moving elements, at least one latch operative to selectively latch at least one subset of said moving elements in at least one latching position thereby to prevent the individual moving elements from responding to the electromagnetic force, an electromagnetic field control system operative to receive the clock and, accordingly, to control application of the electromagnetic force to the array of moving elements, and a latch controller operative to receive the digital input signal and to control the latch accordingly.